"I decided to write this post after having too many heated discussions with many users across many blogs. After hearing repeatedly; 'The iPad will have a better display' or 'It sucks because it's not Retina' I figured it was time to break the argument down and dispel the 'Retina' myth." Fantastic post at The Verge.

I'm fairly amused at how it's taken for a given that the "retina" screen is the best the eye can see. Our photoceptors can detect a single photon. There are ~25,000 cone cells (color) per eye in the fovea, which sees about four square inches at arm's length. So 12,500 cone cells per inch at a couple feet, plus some rods as well.

Obviously, that's not the resolution we see at. Our visual system heavily compresses information in an analog system, then our brain reconstitutes it. Given the overlap, we do a fair bit of superresolution processing while we're at it, so individual photons aren't the lower limit.

Apple's own research points to about 450 pixels-per-inch that a normal person can see at two feet. If you're nearsighted then you can distinguish more. If you're very nearsighted, then a lot more. Does it matter? Probably only with text, where printers and book publishers have long noticed this problem and increased DPI to ridiculous levels (perhaps infinite, as nearby ink dots merge).

And, then there's the issue with color. Many men only can see two types of color (r-g & b), while some women can see four (r, g, g, b). The exact response to light at each wavelength also differs based on genetics. I remember in my high school chemistry class one classmate could see "red" well past 900 nm, while others could barely see it at 700 nm. I think moving beyond RGB color would be cool, but I doubt most people would notice.